The Macau operation has long been under scrutiny but a new in-depth investigation from ProPublica and PBS focused on allegations of improper, and perhaps in some cases illegal, business dealings by Adelson’s Las Vegas Sands company in China. While focusing on the possibility that Sands violated the Foreign Corrupt Practices Act with a $700,000 payment to a Chinese associate, PBS also released documents that bolstered accusations of business ties between Adelson’s shop and Chinese organized crime figures.

PBS reports that Sands was clear that, in order to drive business from mainland China to their Macau casino, they would need to use “junkets” — trips arranged by private companies to ferry high-stakes gamblers to Macau:

Among the junket companies under scrutiny is a concern that records show was financed by Cheung Chi Tai, a Hong Kong businessman.

Cheung was named in a 1992 U.S. Senate report as a leader of a Chinese organized crime gang, or triad. A casino in Macau owned by Las Vegas Sands granted tens of millions of dollars in credit to a junket backed by Cheung, documents show.

Cheung did not respond to requests for comment.

Another document says that a Las Vegas Sands subsidiary did business with Charles Heung, a well-known Hong Kong film producer who was identified as an office holder in the Sun Yee On triad in the same 1992 Senate report. Heung, who has repeatedly denied any involvement in organized crime, did not return phone calls.

Because Nevada gambling authorities forbid doing any business with organized crime, Sands’s Las Vegas gambling licenses could hang in the balance. (Adelson and his company refused to comment for the PBS story.) But Adelson has other issues with his China operations.

Part of Adelson’s Chinese dealings, which came under federal scrutiny in 2011, went through a non-profit called the Adelson Center for U.S.-China Enterprise. According to a WikiLeaks cable flagged by Salon, the association, which was meant to facilitate business between the U.S. and China, was shut down by China after some “missteps” with “funds transfer mechanisms” used by Sands. Unlike competitors, the cable said, Sands lobbied Beijing directly instead of going through Macau authorities. Adelson and Sands deny any wrongdoing related to the federal investigation.